Shigeru Ueno1 · Akihiro Fujino2 · Yasuhide Morikawa3 · Tadashi Iwanaka4 · Yoshiaki Kinoshita5 · Michio Ozeki6 · Shunsuke Nosaka7 · Kentaro Matsuoka8 · Noriaki Usui9
Received: 27 December 2017 / Accepted: 6 February 2018 / Published online: 26 February 2018
© Springer Nature Singapore Pte Ltd. 2018
Abstract
Purpose Clinical guidelines on lymphatic malformation (LM) influencing the airway have been crafted in the Research Project for Intractable Diseases. We herein report an analysis of a nationwide survey of mediastinal LM and the therapeutic recommendations.
Methods Eighty-seven registered cases with mediastinal involvement were analyzed with a review of the literature.
Results Mediastinal LM was located more often in the upper and anterior mediastinum and was found without any accom-panying symptoms in 56/87 cases. Tracheostomy was required in 23/87 cases, mostly < 2 years of age (87%). All patients who needed tracheostomy had a lesion in contact with the airway, while only 55% of those without tracheostomy had contact.
Tracheostomy tended to be placed more when the longer segment of the airway was in contact with the LM. Multimodal treatments were performed in 29 patients, but the lesions remained in most cases, and chylothorax, hemorrhaging, nerve palsy, and infections were noted as complications.
Conclusions In patients with mediastinal LM, tracheostomy may be necessary, especially when the lesion is extensive and contacts the airway. Extirpation of the mediastinal LM may be the only therapeutic option, but in cases with few or no symp-toms, non-surgical treatment should be considered in light of potential postoperative complications.
Keywords Lymphatic malformation · Mediastinum · Child · Tracheostomy
Introduction
Lymphatic malformation (LM) is a rare congenital benign disease caused by hamartomatous development of the lymphatic vessels with unknown cause [1]. The latest
classification proposed by The International Society for the Study of Vascular Anomalies (ISSVA), categorized LM into common (cystic) LM, generalized lymphatic anomaly (GLA), LM in Gorham–Stout disease (GSD), and others.
LM is further sub-classified into macrocystic, microcystic,
* Shigeru Ueno
1 Department of Pediatric Surgery, Tokai University School of Medicine, 143, Shimokasuya, Isehara City, Kanagawa, Japan
2 Department of Pediatric Surgery, National Center for Child Health and Development, 2-10-1, Okura, Setagaya-ku, Tokyo, Japan
3 Department of Pediatric Surgery, International University of Health and Welfare, 537-3, Iguchi, Nasushiobara City, Tochigi, Japan
4 Department of Pediatric Surgery, The University of Tokyo Faculty of Medicine, 7-3-1, Hongo, Bunkyo-ku, Tokyo, Japan
5 Department of Pediatric Surgery, Kyushu University School of Medicine, 3-1-1, Maidashi, Higashi-ku, Fukuoka City, Japan
6 Department of Pediatrics, Gifu University Hospital, 1-1, Yanagido, Gifu City, Japan
7 Department of Radiology, National Center for Child Health and Development, 2-10-1, Okura, Setagaya-ku, Tokyo, Japan
8 Department of Pathology, Dokkyo Medical University Koshigaya Hospital, 2-1-50, Minami-Koshigaya, Koshigaya City, Saitama, Japan
9 Department of Pediatric Surgery, Osaka Women’s
and Children’s Hospital, 840, Murodocho, Izumi City, Osaka, Japan
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and mixed type [2]. The disease appears most commonly in the neck and axilla, and about 10% of cases extend into the mediastinum, potentially causing life-threatening symptoms due to airway obstruction [3–5]. In the Research Project for Intractable Diseases conducted by the Ministry of Health, Labor and Welfare in Japan, we have attempted to draft clini-cal guidelines about LMs (common LM, GLA, and GSD) influencing the airway in children after establishing clini-cal questions (CQs) regarding mediastinal LM. Mediastinal lesions are most likely to be extended from the neck, but LM confined to the mediastinum can be found incidentally or with few symptoms. Airway obstruction caused by the lesion sometimes requires tracheostomy to relieve respira-tory distress, whereas lesions with no or few symptoms can be managed by a more conservative strategy. Since LM con-fined to the mediastinum is a relatively rare condition and may be asymptomatic in some cases, it is difficult to propose appropriate practical guidelines for such lesions.
Thus, a nationwide survey to register pediatric cases with LM was carried out by the Project team in 2015 to eluci-date the optimum treatment approach and to recommend practical guidelines. We also searched for reported pediatric cases with LM confined to the mediastinum and suggested appropriate therapeutic recommendations for mediastinal LM with or without head and neck lesions based on the clinical features accumulated using the nationwide survey and the literature.
Methods Questionnaire
In the Research Project for Intractable Diseases conducted by the Ministry of Health, Labor and Welfare, we tried to establish practical guidelines for treating LM influencing the airway. A nationwide survey to register pediatric cases
with LM was carried out by the Project team in 2015. The survey was an extensive web-based questionnaire with 273 items on clinical features, such as the gender, age at the onset and diagnosis, perinatal history, symptoms, lesion size and site, radiographic and pathological findings, treatment, complications, clinical course, and outcome. Regarding the lesion site, when LM is present within the thoracic cavity, we asked about the exact anatomical site using a figure to define the area (Fig. 1). We also asked about the range and circumference of contact with the airway from the upper pharynx to the intrathoracic trachea, based on radiologi-cal images (Fig. 2). Regarding the treatment, we asked for extensive details of tracheostomy indications, including why a tracheotomy was required, the presence or absence of airway obstruction when the tracheostomy was placed, and whether or not it was temporary. Treatment modalities inquired about included surgery, sclerotherapy, and others, and the outcomes asked about included the mortality and any morbidities.
The questionnaire was advertised by e-mail to every insti-tute employing members of the Japanese Society of Pedi-atric Surgeons and requested that respondents access the
Fig. 1 Definition of the ana-tomical site of the mediastinum
Fig. 2 Definition of the anatomical site of the airway
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webpage http://www.lymph angio ma.net/index .html, which was designed to register both patient data and the responsible surgeon. To avoid reporting duplicate data, we identified over-lapping patients by date of birth, sex, and an endemic number given to each patient.
Data collection and literature search
Collected data on patients with LM with mediastinal involve-ment were used to answer following clinical questions: CQ1—
when is tracheostomy indicated? CQ2—what is the most appropriate therapy for incidentally found mediastinal LM, considering the post-therapeutic complications and outcome?
To answer these CQs, we sorted surveyed data for medias-tinal LM with or without other site lesions and analyzed the data. We also searched for Japanese case reports using the
“Igaku Chuo Zasshi” (Japan Medical Abstracts Society) search engine with the keywords “mediastinum”, “lymphangioma”, and “lymphatic malformation”. PubMed and Scopus were also searched for pediatric cases (≤ 15 years of age) with the same features. Cases with lymphangiomatosis, namely, GLA or LM in GSD, were excluded, and the patients with only mediastinal LM involvement were extracted from the literature search. We collected the patient profiles, including the age, symptoms, lesion site, treatment modality, and outcomes, including post-therapeutic complications, from the extracted articles to make a database. Based on the survey data and literature search, we attempted to answer the above CQs.
Data analyses and ethical considerations
Statistical analyses were performed with the Excel software program ystat2002 (Saitama, Japan). Descriptive statistical methods (median and standard deviation) and a chi-squared test or Fisher’s exact test for two-group comparisons were used for the statistical analyses. A value of P < 0.05 was considered statistically significant.
The survey involving human participants was in compliance with the ethical standards of the institutional and/or national research guidelines and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. The Institutional Review Board of Keio University School of Medi-cine (20120437) and ethics committee of the Japanese Society of Pediatric Surgeons approved this survey on October 10, 2015, and formal consent is not required for this type of study.
Results
Questionnaire results Age at the diagnosis
The web-based questionnaire accumulated data on 1718 cases with LM, and a total of 606 cases with lesions capa-ble of influencing the airway were registered by the ques-tionnaire. Among them, 87 cases with mediastinal LM were extracted, and the clinical features of each case were ana-lyzed for 273 items. The male-to-female ratio was 43:44, and the numbers of patients in each age group at the diagnosis are shown in Table 1. Mediastinal LM was most frequently found prenatally in registered cases (36/87; 41%). The medi-astinum was the only site of LM in 20 patients, while 67 patients LMs at sites other than the mediastinum (data not shown).
Characteristics of the mediastinal LMs
Mediastinal LM was found most frequently in the upper mediastinum (67/87; 77%), followed by the anterior (30/87;
34%), middle (15/87; 17%), posterior (7/87; 8%), and other areas (Table 2). The lesion type was considered to be cystic in 56/87 cases (64%), cavernous in 7/87 (8%), mixed in 16/87 (18%), and unknown in 8. Under ISSVA classification, 51 were diagnosed as common (cystic) LM, 27 as mixed subtype, 8 as GLA, and 1 as GSD (Table 3).
Table 1 Gender and age at the diagnosis
Age Male Female Total
Prenatal 20 16 36
< 1 month 10 7 17
1–12 months 2 4 6
1–5 years 8 7 15
6–15 years 2 2 4
> 16 years 0 1 1
Unknown 1 7 8
Total 43 44 87
Table 2 Site of mediastinal
lymphatic malformations Superior 67
Anterior 30
Middle 15
Posterior 7
Bilateral lungs 2
Heart 1
Rt paravertebral 1
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Symptoms and tracheostomy
The lesion was found without any accompanying symptoms in 56 cases (64%), while in 31 cases, the lesion was found based on symptoms such as respiratory distress (15), stri-dor (9), pleural fluid (4), dysphagia (3), edema/hydrops (2), cough/sputum (2), a fever (2), pain/compression (2), and other symptoms (4) (Table 4). Eleven patients were consid-ered to have had symptoms due to airway obstruction.
A tracheostomy had been placed in 23 cases (20%) when most (20/23; 87%) were < 2 years of age (Table 5). Nine-teen patients required a tracheostomy after they had suffered from airway obstruction (83%), while 4 had had no obstruc-tive symptoms. The reasons for tracheostomy placement in cases without any prior obstructive symptoms included acute swelling due to hemorrhaging and the prevention of respira-tory compromise before therapy (Table 6). Eleven patients
who had had a tracheostomy placed had it closed once they were older (at 2–11 years of age; data not shown).
Tracheostomy and the extent of the lesions
The questionnaire asked whether or not the lesion con-tacted the airway at seven anatomical levels based upon radiological images: the upper pharynx, middle pharynx (above the epiglottis), larynx above the vocal cord, larynx below the vocal cord, cervical trachea, and intrathoracic trachea (Fig. 2). It also included questions regarding the degree to which the lesion circumscribed the airway at each anatomical level it contacted: less than a quarter, a quarter to half, half to three quarters, three quarters to total, and totally circumferential.
The lesion contacted the airway in all patients (except for 3 without imaging studies) who required a trache-ostomy, while contact was made in only about half of those who did not require a tracheostomy (34/64; 55%) (Table 7). On comparing the extent of airway contact of the lesion based on the presence of a tracheostomy, the longer the anatomical level involved, the higher the rate of tracheostomy requirement, although not to a statistically significant degree (Fig. 3).
Treatment for mediastinal LM
In 29 cases, treatment for mediastinal LM was attempted by 39 procedures in total. The treatment modalities included total or partial excision, sclerotherapy, drainage, aspiration, and others. Those adopted in each age group are summarized in Table 8. Sclerotherapy was the most frequent procedure
Table 3 Classification of mediastinal lymphatic malformations
LM lymphatic malformation, GLA generalized lymphatic anomaly, GSD Gorham–Stout disease
Pathological classification
Cystic 56
Cavernous 7
Mixed 16
Unknown 8
ISSVA classification
Common (Cystic) LM 51
Mixed subtype LM 27
GLA 8
GSD 1
Table 4 Symptoms of mediastinal lymphatic malformations
(): Number of prenatally diagnosed cases
None 56
Abnormal X-ray findings 31
Abnormal findings other than X-ray 25
Yes 31 (14)
Respiratory distress 15 (7)
Stridor 9 (3)
Dysphagia 3 (2)
Fluid 4 (3)
Edema/hydrops 2 (1)
Cough/sputum 2 (1)
Fever 2 (1)
Pain/compression 2 (0)
Others 4 (2)
Table 5 Age at tracheostomy Tracheostomy placed 23
Day of birth 2
< 1 year 11
1–2 years 7
5 years 1
7 years 1
Unknown 1
No tracheostomy 62
Not mentioned 2
Table 6 Causes of tracheostomy
Airway obstruction before tracheostomy 19
No obstruction before tracheostomy 4
Acute swelling due to bleeding 1
Prevention from compromise 2
Unknown 1
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adopted. Excisions were attempted in ten cases—via ster-notomy in six, lateral thoracotomy in three, and endoscopy in one.
Among 56 cases found without any symptoms, 16 had been treated by the time of survey. When they were treated, 12 were described as asymptomatic at the time. For these 12 cases, 15 procedures were attempted, and the approaches adopted in each age group are summarized in Table 9.
Treatment outcomes and complications
After treatment, symptom relief was said to be obtained in 22/29 cases, unchanged in 5, and even exacerbated (or new symptoms appeared) in 2 cases (1 each with GLA and cystic LM). There were no residual lesions in 6/29 cases, but in 21 cases, the lesions remained despite therapy and even grew in 1 case with mixed type LM. Complete resec-tion was achieved in only 1 out of 10 attempted excisions (Table 10).
The complications after treatment were described in 8 of the 29 treated cases and included chylothorax, hemor-rhaging, nerve palsy (phrenic nerve, recurrent nerve and facial nerve), and infections. Among the 12 asymptomatic
Table 7 Tracheostomy and airway contact
(P < 0.05; significant difference)
Tracheostomy Airway contact (+) Airway
contact (−)
Required (n = 20) 20 0
Not required (n = 64) 34 30
0 2 4 6 8 10 12 14 16 18 20
1 2 3 4 5 6
Tracheostomy + Tracheostomy-No of Cases
length of contact Fig. 3 Tracheostomy and length of contact
Table 8 Treatment for mediastinal lymphatic malformation: age and modality
s via sternotomy, t via thoracotomy, e by endoscopy, NS not specified
Age Total excision Partial excision Sclerotherapy Drainage Aspiration Others Unknown Number of cases
Prenatal 0 0 0 0 0 0 1 1
< 1 month 0 0 3 1 4 0 0 5
< 1 year 1 (s1) 2 (s1,t1) 4 2 1 1 (pleural adhesion) 0 8
1–5 years 2 (s1,t1) 2 (t1,e1) 4 3 0 1 (proplanolol) 0 10
Adult 0 0 0 1 0 1 (proplanolol) 0 2
NS 1 (s1) 2 (s1,t1) 1 0 1 0 0 3
Number of procedures 4 (s3,t1) 6 (s2,t3,e1) 12 7 6 3 1 29 cases
39 proce-dures
Table 9 Treatment for asymptomatic mediastinal lymphatic malformation: age and modality
s via sternotomy, t via thoracotomy, e by endoscopy, NS not specified
Age Total excision Partial excision
Sclero-therapy Drainage Aspiration Others Number
of cases
< 1 month 0 0 1 0 2 0 2
< 1 year 0 0 1 0 0 0 1
1–5 years 2 (s2) 2 (s1,e1) 2 1 0 0 6
Adult 0 0 0 0 0 1 (proplanolol) 1
NS 0 1 (t1) 1 0 1 0 2
Number of procedures 2 (s2) 3 (s1,t1,e1) 5 1 3 1 12 cases
15 proce-dures
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cases treated, 2 were complicated with hemorrhaging and nerve palsy (Table 11). There were no deaths related to therapy, although one patient died of GLA despite multi-modal treatments.
Long‑term effects
The questionnaire asked about the degree to which the patient’s everyday life (at the time of the survey) was affected due to the lesion. Most of them (66/85; 76%), including 20 cases who had undergone treatment for mediastinal lesions, reported no inconvenience in their daily life. However, 9 out of 29 cases treated were said to have had their lives some-what affected, including 3 who found their lives severely impaired. Of the 8 cases with complications after treatment, 2 with nerve palsy after excision reported having their lives impaired moderately (Table 12).
LMs confined to the mediastinum
Twenty registered patients with LM confined to the medi-astinum were analyzed (Table 13). Seven cases were prena-tally diagnosed, and 14 were asymptomatic when the lesion was found. Excision was attempted in two cases, but more conservative therapeutic modalities were selected for the other six cases. The LM lesion remained after treatment in five out of the eight cases treated (data not shown).
Literature search for LMs confined to mediastinum
As a result of the search, the first reported case was found in a German paper by Schmincke in 1920 [6], and 100 pediatric cases were ultimately collected. Many had been previously reviewed by Moore et al., Takamatsu et al., and Niho et al.
[7–9].
The distribution of the age at the diagnosis and the symp-toms are shown in Table 14. Thirty cases were diagnosed when they were < 12 months. The anterior and superior mediastinum were the most frequently occupied regions (77/100) (data not shown), and respiratory distress was the most frequent symptom at the onset, being noted in 32
Table 10 Treatment outcomes
(): Number of asymptomatic cases Symptoms
Symptoms Relieved 22 (8)
Unchanged 5 (3)
Exacerbated or new symptoms 2 (1)
Residual disease
None 6 (2)
Yes 21 (9)
Exacerbated 1
Unknown 1 (1)
Table 11 Post-therapeutic complications
(): Number of asymptomatic cases
Chylothorax 2
Hemorrhaging 2 (1)
Phrenic nerve palsy 1
Recurrent nerve + Facial nerve palsy 1 (1)
Infections (mediastinitis, SSI) 2
Table 12 Long-term sequelae (as effects on the everyday life)
a Chylothorax, infection
b Chylothorax, hemorrhaging
c Nerve palsy
d Hemorrhaging Effect on the
everyday life Treatment (+) Treatment (−) Total
Complica-tion (+) Complica-tion (−)
None 4a 16 46 66
Mild 2b 1 2 5
Moderate 2c 1 6 9
Severe 1d 2 2 5
Total 9 20 56 85
Table 13 Cases with lymphatic malformation confined to the medi-astinum
(): Number of asymptomatic cases Age at the diagnosis
Age Number
of cases
Prenatal 7 (6)
< 1 month 2 (1)
1–12 months 1 (0)
1–5 years 6 (4)
6–15 years 2 (2)
Unknown 2 (1)
Treatment
Total excision (via sternotomy) 1
Partial excision (endoscopic) 1
Sclerotherapy 3
Drainage 3
Aspiration 2
Pleural adhesion 1
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cases, followed by a fever in 24, pain in 16, and cough/spu-tum in 11. A variety of presentations were noted, including chest wall mass/swelling, stridor, fluid collection, cyanosis, neck/axillar swelling, hoarseness, and others. Of the 11 pre-natally diagnosed cases, 2 presented with fetal hydrops [10, 11], and 4 were asymptomatic after birth [10–12]. Thirty cases were found incidentally. The number of asymptomatic cases increased with age: 6/30 (17%) among infants, includ-ing prenatally diagnosed ones, 9/39 (23%) among toddlers, and 15/32 (47%) among school-aged children.
Surgical excision was the initial treatment in 84 cases, and 3 underwent excision after sclerotherapy. Sclerotherapy in nine cases, prenatal aspiration in two [11, 12], and pleu-rodesis and octreotide in one each were attempted.
Three fatal cases were reported, including the first 1 described in 1920 [6] and 2 from Japan with short descriptions; 1 was a neonate who died after sclerother-apy [13] and the other was a 12-year-old boy who died after recurrence due to an overwhelming streptococcal infection [14].
Fourteen cases developed complications after treat-ment. Six suffered from phrenic nerve palsy (one also with recurrent nerve palsy), and chylothorax or pleural effu-sion occurred in six cases [7, 8, 11, 13, 15, 16]. Cases with
complications accounted for 5 of 27 (19%) neonates/infants, 6/39 (15%) toddlers, and 3/32 (9%) school-aged children.
Treatment for the 29 patients without any symptoms, including those prenatally detected, was surgical resection, except for 3 who received fetal intervention and/or sclero-therapy. Among them, phrenic nerve palsy and chylothorax occurred in two out of eight cases after surgery. Ono et al.
described a case that was observed without any intervention after prenatal detection of the LM [17].
Discussion
The prevalence of LM is reportedly 1–3 in 10,000 live births, and it is common in the neck and axilla, with 10%
of cases showing mediastinal extension [1]. Our nationwide survey in Japan and thorough document retrieval allowed us to accumulate reported pediatric cases of mediastinal LM with or without lesions at other sites. Cases with medias-tinal LM comprised 87 of the 606 (14.3%) surveyed cases with head and neck lesion that might influence the airway.
Patients with LM confined to the mediastinum have been reported to account for < 1% of cervical cases [3–5]. In this survey, there were 20/606 (3.0%) cases with LM confined to the mediastinum, accounting for 1.1% (20/1718) of all registered LM cases, which indicates that this is indeed a rare entity.
LMs are not exactly neoplasms, and they account for only a few cases among mediastinal masses (0.7%-4.5%) [18, 19]; indeed, only 10 LM cases were found among 150 (6.7%) mediastinal mass lesions based on a questionnaire administered by Yano et al. [20]. Regarding the number of cases in the total population, only 2 cases were identified after a health checkup by chest X-ray for 212,708 preschool children, indicating a prevalence of 0.9 per 100,000 [21].
The mediastinal LMs in the cases detected in the survey and literature search were mostly located in the anterior and/
or superior mediastinum, regardless of the presence of LM at other sites. Mediastinal lesions tend to develop near the neck and face. Embryologically, the lymphatic network develops from or around the five sites of lymphatic anlage, including the jugular lymph sac in humans [22, 23]. LMs may also develop as a result of sequestration of portions of the primi-tive lymphatic anlage [23]. Given that LM most commonly develops in the facio-cervical region, with the anterior and/
or superior mediastinum located near the jugular lymph sac, mediastinal lesions tend to develop in this portion of the thoracic cavity.
These lesions can occupy the thoracic cavity or outlet and compress the airway, and they are also susceptible to infection; as such, they can cause a variety of respiratory distress symptoms due to airway obstruction. Malfunction of the lymphatic drainage can result in pleural effusion/ascites
Table 14 Reported cases with lymphatic malformation confined to the mediastinum
(): Number of asymptomatic cases Age at the diagnosis
Age Number
of cases
Prenatal 11 (5)
< 1 month 6 (0)
1–12 months 13 (1)
1–5 years 38 (9)
6–15 years 32 (15)
Total 100 (30)
Symptoms
None 30
Yes 69
Respiratory distress 32
Fever 24
Pain/compression 16
Swelling/mass 14
Cough/sputum 11
Stridor 7
Fluid 6
Cyanosis 5
Hoarseness 3
Others 5
Not mentioned 1
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or hydrops fetalis [10, 11]. When cystic hemorrhaging or infection occurs, it causes swelling, chest pain, neck/axillar swelling, hoarseness, and even superior vena cava syndrome [24, 25].
Superficial LMs are easily noticed soon after birth, and LMs located at the mediastinum can be detected by further studies for head and neck LMs. Our survey data showed that LMs were most frequently found prenatally, suggesting that these lesions are easily detected by fetal ultrasonography in Japan. When LMs involve the mediastinum, some patients present with symptoms soon after birth, especially when the lesions also involve the head and neck region. Some reported cases had symptoms as early as the neonatal period, even when the lesion was confined to the mediastinum. Even in cases where the lesion cannot be seen from the outside, it can cause symptoms and respiratory failure in early infancy, which necessitates intensive care.
When a patient with LM suffers from airway obstruc-tion, airway management, including the placement of a tracheostomy may be warranted for relief. In the surveyed patients who required a tracheostomy, it was typically placed at < 2 years of age. However, it should be noted that only 20 of the 87 cases required a tracheostomy, and 11 had their tra-cheostomy closed afterwards. Ex utero intrapartum therapy (EXIT) has been introduced in prenatally diagnosed patients with potential airway obstruction after birth, and LM is a disease indicated for EXIT; and a tracheostomy is, there-fore, the final option for securing the airway during EXIT [26, 27].
Our survey and literature search revealed some cases detected incidentally, either pre- or postnatally. The number of reported asymptomatic cases increased with age, with the distribution showing that incidental discovery coincides with the timing of routine health checkups (either by ultra-sonography or chest X-ray). Although many cases have been discovered by fetal ultrasonography, there have been reports of spontaneous regression of the cystic mass in the medi-astinum [28]. There may, therefore, be some patients with mediastinal LM in whom the lesion remains part of their body, causing no impairment and remaining undetected.
We must consider the indications for tracheostomies in patients with LMs that can potentially cause airway obstruction. The results show that all surveyed patients who required a tracheostomy had lesions in contact with airway, and that the longer the extent of airway contact with the lesion, the more often a tracheostomy was required, albeit not to a statistically significant degree. This may suggest that EXIT is indicated for prenatally diagnosed patients with LMs that might compromise the respiration after birth based on the extent of contact. We may also be able to predict the need for tracheotomy to prevent respiratory distress before therapeutic intervention. Further studies will be required to resolve these questions.
The goal of LM treatment is the maintenance and recov-ery of the functional and aesthetic integrity. One currently available therapeutic modality other than surgical resection is sclerotherapy using agents such as OK-432, bleomycin, doxycycline, and ethanol [29]. The treatment modalities applied in the accumulated cases were varied, as shown in Tables 8 and 9. In cases of LM confined to the mediastinum, there is no cosmetic backwash. As such, the indications for its treatment are solely for symptom relief, when symptoms are present. If mediastinal LM causes severe symptoms and is invasive, complete resection to prevent recurrence may be performed to relieve the symptoms [7, 8, 11, 13, 15, 16].
In 29 registered cases, various treatments for mediastinal LM were attempted across 39 procedures in total, including 12 cases without any symptom at that time (Tables 4, 5).
Excision was attempted in 10 out of 29 cases. In most of the reported cases, surgical resection was selected as the initial treatment. It is speculated that, since the introduction of sclerotherapy, surgical resection has been selected as the treatment modality less frequently.
While treatment can achieve symptom relief, the lesion remained even after attempted resection in most registered cases. Complications after treatment included chylothorax, hemorrhaging, nerve palsy, and infections, all of which were postoperative. Acute complications, such as chylothorax or infection, only affect patients temporarily, but it was sug-gested by the survey that complications such as nerve palsy might influence the long-term quality of life among patients.
Whether or not these complications were truly responsible for patients’ decreased quality of life was unclear, since we did not ask the reason for the inconvenience. However, our review on LM confined to the mediastinum showed that the younger the patient, the higher the morbidity rate. We should bear in mind that surgical resection can result in long-term complications along with surgical scarring.
In cases with no or few symptoms, non-surgical treatment should be sought, as the complication rate tends to be high otherwise. Regarding alternative options, lesions are known to become swollen after sclerotherapy, and the effect of such therapy on the airway is a concern. Side effects of the scle-rosing agents bleomycin and doxocicline have been reported [29, 30]. There is an interesting case report in which Kampo medicine was effective in shrinking an intractable LM [31], but further evidence for its efficacy is necessary. Surgical resection should be attempted with well-informed consent, especially regarding postoperative sequelae, due to potential long-term complications.
We recommend that prenatally detected LMs be followed up after birth without treatment if they are asymptomatic.
Surgical intervention should be avoided in pediatric cases with few or no symptoms suggested by imaging studies to be LMs.
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